1. Field of the Invention
Embodiments of the invention relates to a knitted fabric having a first covering layer, a second covering layer and an arrangement of pile threads embodied as spacer threads between the first covering layer and second covering layer. Each covering layer includes multiple stitch rows arranged one after another, spacer threads are provided with different lengths, and spacer threads of equal length are woven into each stitch row.
Furthermore, embodiments of the invention relate to a method for producing a knitted fabric in which a first covering layer is produced with a series of first stitch rows arranged one after another in the direction of production and a second covering layer is produced with a series of second stitch rows arranged one after another in the direction of production and in which pile threads are arranged between the two covering layers as spacer threads and woven into the covering layers. A distance between the covering layers is altered and regions with varyingly long spacer threads are produced.
Further embodiments relate to a warp knitting machine having two knitting regions for producing respectively one covering layer. The distance between the knitting regions can be adjusted by an actuating drive, and having at least one pile guide bar which can be moved with its guide needles back and forth between the knitting regions.
2. Discussion of Background Information
Knitted fabrics with two covering layers between which spacer threads are arranged are also referred to as “knitted spacer fabrics.” A knitted spacer fabric of this type has, for example, relatively good air permeability so that for products that are used in connection with the human body, it is preferably used where the wicking-away of moisture is desired. Examples thereof are chair upholsteries, mattresses or backpack straps.
In the simplest case, a knitted spacer fabric of this type has a constant thickness. In this case, the knitted fabric is produced with the aid of two needle heads which have an unchanging and constant distance to one another. Between the two needle heads, at least one pile guide bar is disposed which arranges the pile threads between the covering layers as spacer threads.
In order to have greater freedom in the design of the knitted fabric, it is known from German Patent Application No. DE 10 2008 047 684 A1, for example, to alter the distance between the needle heads by an actuating drive. The distance can also be altered during the manufacture or production of the knitted fabric. However, this change in distance is always linked to a change in thickness of the knitted fabric over the entire width thereof.
A similar approach is known from U.S. Pat. No. 7,913,520 B1.
A knitted fabric having a thickness that can also be variably selected in the width direction is known from DE 41 40 826 A1. However, for this purpose, it is necessary to divide at least one or a number of the bars which carry the knitting tools. This makes a control, and therefore an operation, of the warp knitting machine extraordinarily complicated.